ABSTRACT
Despite the great adaptability exhibited in mammalian evolution, temperate North America is the origin for all of South Florida’s native terrestrial mammals. The only native species having an origin distantly traceable to the tropics, yet also having entered Florida from the north, is the Virginia opossum, North America’s only marsupial or pouched mammal. However, fossils prove that land mammals from the South American tropics had invaded Florida by about 2.5 million years ago,** after the emergence of the land bridge between North and South America (see Chapter 1). Despite this connection, most land mammals of tropical origin perished in Florida during glacial periods when climatic conditions were cool and, more importantly, dry, thus eliminating their wetforest habitat.183,373,642
Although not naturally reaching southern Florida, a distinctive tropical mammal that has reached the Florida panhandle naturally is the nine-banded armadillo. This species is now common nearly throughout Florida wherever sandy soils occur including the northern Big Cypress Swamp, and there are sporadic records for Everglades National Park. The armadillo populations of the peninsula have been shown to be from human introduction.84,332
Marine and flying mammals have tropical representation in Florida. The marine access route is obvious just as with tropical marine reptiles. Marine mammals are covered in a separate section at the end of this chapter. Bats, the only flying mammals, could have entered Florida from the tropics as well as from temperate North America. Six species have been recorded in South Florida, two of which apparently came directly from the tropics, and only one, the mastiff bat (Eumops glaucinus), is represented by a viable but very small population, which is primarily confined to developed areas around Miami where its roosts are in houses and buildings. Overall, however, bat populations in the region are so small that their ecological role is negligible.84,275,291,331
In the faunal history of Florida there is another ecological factor of more than academic interest. Numerous prehistoric animals, including what are dubbed “megafauna” (horses, mammoths, mastodons, giant ground sloths, giant tortoises, and
* The main sources for this chapter are references 291,331,410, and 647. ** A few mammals of tropical origin first appear in Florida’s fossil record nearly 9 million years ago, probably having reached North America by “island-hopping.” While the land bridge was forming, closely spaced islands would have emerged as forerunners of a complete land connection.373 The effect of the land bridge in facilitating the movement of land animals was gradual, not abrupt.
